Reputation systems have been developed for use on the Internet. Such systems allow users to provide ratings for websites, items being bought and sold, news items, service providers, or ratings of other users. The objects being reviewed using these systems are objects that are themselves explicitly digital (such as news items) or else are given a digital identifier (such as a product identifier on Amazon or a seller's identifier on eBay). Existing reputation systems aggregate such information into a reputation score and present it to the users. Reputation systems can help improve the quality of digital interactions.
Other systems addresses information stored and retrieved according to location. For example, in Waze (www.waze.com) a user can provide information with respect to a location, such as an accident on a road. Other users are given that information if the location is relevant to them, such as it falls on a route that they are navigating.
In the off-line world, people sometimes share information with each other about physical objects in their environment that they find interesting (e.g. objects that are especially useful or threatening). Such sharing has not been fully supported in existing computer and mobile technologies.